


Wicked Game

by The_Anglophile



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: AU, F/M, Genderswap, Warnings at END of fic
Language: English
Status: Completed
Published: 2013-03-18
Updated: 2013-03-18
Packaged: 2017-12-05 16:51:37
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,826
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/725607
Author URL: https://archiveofourown.org/users/The_Anglophile/pseuds/The_Anglophile
Summary: <blockquote class="userstuff">
              <p>Sherlock is openly fascinated with his older sister, Mycroft, flirting with and teasing her at every opportunity. She doesn't mind the attention - to a degree. During one exceedingly dull dinner party at Mummy's house, he goes perhaps a little too far...</p>
            </blockquote>





	Wicked Game

**Author's Note:**

> A/N: Warnings are at the end of the fic.
> 
> Written for [this kinkmeme prompt.](http://sherlockbbc-fic.livejournal.com/19743.html?thread=117413407#t117413407) Also [here](http://iguana-dog.livejournal.com/1220.html) on LJ.

  
If things were a bit out of the ordinary between her and her brother, Mycroft knew why. She had made the mistake, back when Sherlock was twelve, of filling the boy in on the details he was curious about that Mummy hadn't included in her 'birds and bees and growing boys' speech. She had still thought of her brother as child at the time, the seven years between her age and his nearly convincing her that he would always be small, and she hadn't noticed his increased curiosity and sharpened gaze when looking at her, the little hints of a man peeking out through the babyish face. He had sat on her bed listening with rapt attention as she explained certain mysteries to him, his face flushing occasionally, but never turning away. He had asked a few impertinent questions, and she had brushed them off as simple childish bluntness and answered them patiently; she had always encouraged his bright inquisitiveness, and hadn't thought to do differently this time.

_She'd said all women's nipples were a bit different, so what were hers like? Did she have hair under her arms? Could he see it?_

She credited this misstep of hers with everything that had occurred between them since, or at least everything that she would never care to mention to another person. He'd become a mischievous, but very appealing teenager, staring a little too much, sitting a little too close, touching her hair, then later coming to her humbly for advice on his problems and playing the part of the sweet younger brother so well that she would forget the earlier transgressions.

Mycroft was returning home this weekend for a dinner party that Mummy was throwing for her society friends; there was one in particular she wanted Mycroft to meet who was supposed to be working in the department of government that Mycroft wanted to enter. Mycroft was certainly looking forward to meeting this potential useful contact, but as she walked up the steps to the door of her childhood home, the only thing on her mind was Sherlock. He had been growing up quickly into a handsome youth and she couldn't deny to herself that she wanted to see if he had changed any further in the months she'd been away. She didn't have to wait long to find out, for it was her brother who opened the door.

"Mycroft," he said warmly, his voice betraying none of his former childish enthusiasm, but his eyes telling another story. He was learning to control himself, Mycroft thought with approval as she stepped through the doorway.

"Hello, my dear boy," she replied fondly, handing him her coat and umbrella, which he dutifully took to the closet before returning to her. She looked up at him - he was now taller than she and still growing - taking in his appearance before smiling knowingly and saying, "Two hours?"

Sherlock flushed and looked at his feet for a moment before regaining his composure and meeting her gaze again. "One and a half," he replied.

Her eyes narrowed. "One and forty-five," she countered.

He sighed, a smile tugging the corner of his mouth. "One and forty-five," he assented. Mycroft smiled at him. She always knew how long he'd been preening and primping for her arrival. This was a new record. He'd probably changed clothes four or five times.

She opened her arms and he stepped into them, his large, warm hands pressing the small of her back, bringing her close. Too close, if she thought about it too much, but she avoided doing so as a rule. She knew that he loved her curves, for whenever they went to an art museum together, he always spent a little extra time admiring the full-figured statuary that they passed. She returned his embrace gladly, no longer resisting his attempts to pull her fully against him, as she had done when he'd first tried it. To have her breasts pressed against her little brother felt deliciously wrong, gave her a nervous thrill like few she'd ever known before... but now she was thinking about it too much. She pulled away, softly stroking his cheek with a hand as his piercing eyes consumed her. He was so pretty at this age. No longer a boy, and not quite a man. Skin perfectly smooth, but with adult musculature underlying it.

"You're looking well, Sherlock," she said, and moved past him to go find Mummy.

***

At bedtime, Mycroft heard a soft tap on her door, as she had expected to. "Come in," she called. Sherlock entered, shutting the door quietly behind him. He was in his dressing gown, and apparently not much else, as she couldn't see any pyjama trousers or a t-shirt hiding beneath the blue cloth. She raised an eyebrow slightly as he approached her where she sat at her vanity, removing her lipstick. When had he ceased wearing pyjamas?

He perched on the end of the vanity, legs sprawling carelessly and allowing his dressing gown to fall open a bit, revealing a long, muscular thigh covered sparsely with fine hair. Mycroft allowed herself a sideways glance at it, then returned her attention to her own face, carefully wiping away the remains of colour from her lips. Sherlock sat quietly, content to watch her as he always had. He still seemed mesmerised by her daily transformations whenever he was allowed to witness them, and Mycroft was a little surprised that he was just as interested in her looks when she had no makeup on as when she did, perhaps even more so.

She took her time with her eyes, delicately removing the last of her daily mask and enjoying the ability to rub her face freely again. When finished, she turned to Sherlock and he greeted her at last.

"Good evening, sister," he smiled.

"And hello again, brother," she replied.

"Tomorrow, I thought we might go into town to the Andrews-Price gallery. I hear they have an excellent exhibition of drawings right now."

"That sounds lovely," Mycroft agreed. Gallery-hopping was one of their favourite bonding activities; Sherlock was so wonderfully vicious in verbally tearing apart inferior work, it amused Mycroft greatly to listen to him. He had a fine eye for detail. "What time?"

"After lunch, perhaps. I know Mummy wants to cook for you. She's been trying things out on me all week."

"And you haven't fully appreciated them, have you!" she reprimanded, squeezing one of his bony knees. "You're so thin, my dear."

"You know I'm too busy to eat, Mycough," he said in mock protest, and she smiled at the pet name. That's what he'd called her before he could pronounce her name properly.

"Well, at the very least you can get some real sleep, can't you?" She rose. "None of this 'four hours is fine' nonsense. Don't look at me that way, Mummy tells me all about you. Now say goodnight."

Sherlock stood and leaned down to kiss her. As their lips met, she felt his hands on her, one on her shoulder, the other on her side, just above her waist. It wasn't just a quick peck on the lips, hadn't been for a year now that she thought about it, though their mouths remained modestly closed, and she didn't mind when he finished one soft kiss only to place another on the corner of her mouth immediately after. What she did mind was when his hand slid up to cup her breast, thumb brushing over the nipple brazenly. That was really a bit too much! It was true, the overlong kisses she had allowed - ok, encouraged - but what cheek! She slapped his hand and he instantly dropped it, backing away from her and trying to conceal the pleasure in his face.

"Goodnight, Sherlock," she said firmly, in dismissal.

"Goodnight, Mycough." His long, lean form padded silently from the room, leaving his somewhat flustered sibling behind.

*** 

Sherlock was conspicuously absent at breakfast the next morning, and Mycroft hoped that he was sleeping in as she'd suggested. She did honestly worry about him. He was careless with himself. She and Mummy enjoyed a breakfast chat about Mummy's latest hybrid roses and the exquisite colours she'd acheived this time, before Mycroft excused herself to go get showered and dressed for the day.

She passed by Sherlock's closed door on her way to the bathroom they shared, and thought that was a good sign. A closed door in the morning usually meant he was still inside. She pushed the bathroom door open. Her eyes widened involuntarily as she saw Sherlock standing naked before the mirror, leaning in close to the glass trying on her lipstick.

His back was to her, and though he must have noticed her presence, he didn't acknowledge it and carried on delicately lining his lips. She couldn't help staring a bit at the agreeable sight before her; the long graceful legs, small shapely buttocks, thin waist, and broad, muscled back and shoulders were by no means an eyesore.

Sherlock looked up and smirked wickedly at her in the mirror, pursing his big lips beautifully, and she rolled her eyes and moved swiftly onward to her bedroom, the image blazing in her mind's eye. What a strange and thoroughly poorly-behaved brother she had! This would certainly explain why her lipsticks never seemed to last while she was at home. She felt oddly titillated finding that she'd been sharing them with him unknowingly all this time. Well, perhaps 'unknowingly' was the wrong word. She'd had her suspicions, but they fell into the category of things she didn't let herself think too much about.

The two of them managed to prepare for the day and make it through lunch without further incident, and Mycroft then hunted around the house until she found Walter, convincing him to stop fiddling with a broken doorknob and drive them to town. He amiably agreed, as he usually did, and went to fetch the car while Mycroft rounded up Sherlock. He was dressed all in black today and looked especially tall and sleek, as was no doubt his intention. The lipstick had disappeared. Mycroft had donned a slightly more casual suit than she usually wore, slate grey with a closely-tailored rose blouse, the skirt just above her knees baring her softly rounded calves. They stood on the front steps, trying not to obviously admire one another as Walter pulled up in the car.

Sister and brother slid into the back seat, Mycroft taking the window to enjoy the scenery, Sherlock seated in the middle, next to her. After some time in silence on the road Sherlock leaned towards her.

"Do you know why I wear your lipstick?" he said low in her ear, and she inclined her head slightly with curiosity. "It's because your lips were the last to touch it." A pleasurable chill went up her back at his words, but she retained her calm exterior.

"It suits you," she replied coolly, and he smiled a little, sitting back in his seat.

They entertained themselves on the drive by making swift deductions about the people they passed by, Mycroft gently correcting Sherlock's mistakes, and Walter marvelling at the pair of them in his avuncular fashion, occasionally challenging their assertions just to annoy them and make them elaborate. He dropped them by the old college and, having agreed on a time and place to collect them again, returned the way he had come.

Students were wandering in gaggles, enjoying the fine weather, some picnicking on the grass, distant others busy at various sporting activities. It was quite nostalgic for Mycroft to revisit the place. Sherlock led her to the gallery he'd spoken of, and as they entered and her eyes began to take in the images, she knew she'd been tricked. Voluptuous forms in a creative variety of clinches greeted her gaze. It was an erotic art exhibition. She might have known.

Sherlock was already in the midst of it, and he beckoned her from where she stood at the door, his expression betraying absolutely nothing. He _had_ become skilled at concealment, hadn't he? She sighed and resigned herself to her fate. Two could play at 'stone faces', after all.

She joined him and they browsed slowly through the drawings, passing tittering students and lovers hand-in-hand, along with an old woman who, despite her look of outrage, could clearly not drag her eyes away from the offending pictures.

Presently, Sherlock stopped in front of an orchid-like drawing of a vulva and considered it with his intense yet detached stare. He motioned to it. "What do you think?" he asked Mycroft, then continued before she could answer, "I think it's quite strong. Really, it's almost aromatic, almost flavourful. The light indications of wetness almost convince one of sweetness and craveability, like the attraction of a flower to a bee." He'd been looking at the art as he assessed it, but now he turned his gaze on Mycroft. "The warm softness is almost palpable."

He was speaking quite plainly, so that anyone who happened to be passing could easily hear his words, and though Mycroft had the nervous urge to turn and leave, she wasn't about to let her younger brother best her at this game. Her expression as cool as ever, she replied, "It _is_ charming. But I think this piece outdoes it for drama." Here she led him to a detailed image of a man with his face half-obscured by the thighs of his lover. His tongue extended up from his open mouth and disappeared between a pair of lips of the exclusively female variety.

"The closeness of this drawing, the heavy weight of the thighs, is positively suffocating," Mycroft began, keeping her eyes on Sherlock. "The imagination easily summons the sensations one would feel in such a situation, with one's head pinned in such a fashion. The heat and humidity between the legs would be overwhelming, nearly tropical, and the encompassing velvety flesh would leave one in a state of powerless pleasure, perfectly smothered by skin, and nearly drowned in juices."

Sherlock blinked and swallowed hard, eyes darting away from Mycroft's for a moment, cheeks colouring just slightly, and she raised an eyebrow at him, enjoying his lapse of control. When she chose a new piece to go look at, he followed docilely, silent as a shadow.

After the gallery Sherlock took Mycroft to her favourite bakery and sweet shop and bought her one of her favourite truffles, the Grand Marnier. They sat at the little table by the window, she slowly savouring the truffle, and he sipping water and savouring the sight of her. She made a small show for him, discreetly kissing and sucking on the truffle, rather than simply biting it, licking her lips primly and eyeing him to make sure he was watching. His attention was fully captured.

On their way out of the shop, Sherlock stroked a hand briefly over Mycroft's ample bottom. She jumped. "Naughty!" she hissed at him, but he had been careful; no one was looking their way.

***

Once the two arrived home again, they found the dinner party guests chatting and enjoying hors d'oeuvres in the parlour. The contact Mummy had wanted Mycroft to meet turned out to be a real bore, and a talkative one at that. Pity. Mycroft made sure to endure his conversation for a sufficient length of time to make an impression, then slipped away to mingle with the other guests.

Once supper was served, everyone moved to the dining room, Sherlock following Mycroft to their usual seats at the far end of the table. Their mother sat at the opposite end, next to their father's empty chair, with all the guests filling in the spaces in between. The meal went reasonably well up until dessert, at which point the cognac appeared and transformed several of the guests into hideously dull windbags who began to dominate the previously bearable conversation.

Mycroft sipped coffee, allowing her mind to wander to her work duties on Monday morning, when, to her great surprise, she felt a large, warm hand on her thigh, pushing upward under her skirt, fingers sliding as far as possible between her closed legs. She very nearly stomped on Sherlock's foot with the heel of her shoe, but then thought better of it. His face was perfectly emotionless, looking casually around the table as if he wasn't groping his sister beneath it, but she was quite sure she could throw his smug composure. She carefully pulled her skirt up a bit and spread her legs, giving him a challenging glance. He would never take that dare. Never.

He caught her glance, looking a little surprised, and Mycroft felt a powerful chill sweep up her back as his hand did indeed venture further up her thigh, until his fingers discovered her lack of undergarments. He paused at this unexpected revelation, then gave her another quick look, the devil in his eyes, the smallest of smirks on his lips. For her part, Mycroft was frozen with nerves at her brother's unexpected boldness. She hadn't gone bare today for his benefit, though he was surely thinking it, and she wished he would remove his hand before anyone noticed anything amiss between the two of them. She could hardly risk pulling his hand away; surely someone would see? The old blowhard at the other end of the table was still jawing away, and thankfully everyone present was polite enough to continue to give him their attention, at least with their eyes. Mycroft could see that some of those eyes were glazed over, but at least none of them were wandering the table.

She felt Sherlock slip his middle finger down past her clitoris and very softly begin to explore her labia, examining their texture and pliancy with the pad of his finger, undoubtedly memorising every detail. His other fingers rested comfortably to the sides, his palm warmly covering her mons. Mycroft forced herself to pick up her coffee cup and take a sip, determined to look perfectly normal no matter what occurred, but she soon felt a rush of heat to her cunt and knew that her skirt would need taking to the cleaners. Sherlock now slid two of his fingers through the wetness that had appeared, running them around the sides of her cunt, teasingly dipping the tip of a finger in before immediately removing it. Mycroft had to work to control her breathing.

Suddenly, the woman seated just down the table from Mycroft turned to her and asked her about her job, evidently too bored by the other proceedings to pay any more attention to them.

"Well, Ms. Holmes, I don't believe you've told me exactly what it is you do."

Through a rush of adrenaline, Mycroft managed to give a normal answer to the question, though when she leaned back in her chair, Sherlock took immediate advantage of the improved angle of her hips and forcefully pushed one of his long fingers into her, pressing in until he was past the second knuckle. Mycroft disguised her gasp by raising her hand to her mouth and clearing her throat. The other woman noticed nothing, but turned to Sherlock.

"And do you mean to follow your sister, or do you have other plans for the future?"

Mycroft allowed herself to look at Sherlock as he replied to the question, his face perfectly composed; she could hardly believe the situation he was currently putting her through. As he spoke, Mycroft could feel her cunt getting hotter and wetter in response to her brother's finger, opening and wanting to be filled fully. She squirmed slightly in her seat. He began stroking her g-spot and she was very grateful when their conversational companion turned and began to speak with someone else.

When Mycroft's breathing was noticeably heavier, Sherlock drew his finger from her cunt and began sliding it over her clit. She shivered involuntarily at the touch and he pressed more firmly, moving his finger in small, slow, rhythmic circles. Mycroft felt her face and chest begin to flush, and was very grateful for the dim lighting in the dining room. She wished Sherlock would go faster, but he kept up his stubbornly slow pace, occasionally dipping back down into her cunt for more lubrication. The feeling that began to spread outward from her clit was delicious, and it took a great deal of effort to maintain her stiff posture when she wanted very much to move her hips against the hand that was pleasuring her.

After what seemed an eternity, she felt herself pushed over the edge. She inhaled sharply through her nose, her back straightening tensely as she used all her self-control to keep her face impassive and her hips still. She bit her tongue as the fiery heat of the orgasm spread from her cunt down her thighs and up her lower belly, steeling her body against the tremours that began to run through her. Due to her absolute stillness, and Sherlock's slow method, the usual brief, star-bright kick of intense pleasure was replaced by a gradual flaring of ecstasy, like an upwelling of molten rock in a volcano. It was like nothing she'd ever felt before, and her tongue was bleeding by the time it was finished.

Mycroft sighed as softly as she could manage and leaned back in her chair, her body slumping a little with relaxation despite her best efforts. Not a soul had noticed anything unusual at the siblings' end of the table, for which she was deeply grateful. Sherlock glanced at her and withdrew his hand, leaving her cunt feeling a little cold and bare. He caught her eye and raised his hand to his nose, sniffing softly, then proceeded to very indiscreetly lick his sticky fingers clean. Mycroft felt a pulse of pleasure in her cunt at the sight, a rush of excitement at the obscenity of it, and slipped a foot out of its shoe, rubbing it up his leg in silent appreciation.

"Sherlock!" a voice barked from the other end of the table. It was Mummy. "Where are your manners?" Eyes began to shift in their direction.

"I'm sorry, Mother," Sherlock said deferentially, casting his eyes down in simulated contrition, hand leaving his mouth to fold into his lap. A convenient place for it, Mycroft thought, a quick glance revealing his painfully constrained erection to her.

Mummy muttered something about having raised a wild animal, then begged the woman who had been speaking to continue. The other guests' attention returned to the mind-numbing topic at hand, and Mycroft took the opportunity to turn her head and really look at her brother. He looked back at her, his smug expression clearly stating that he'd won this round of the dangerous game they so loved to play. She smiled her agreement, knowing that he couldn't keep the upper hand forever.

The End (?)

**Author's Note:**

> WARNINGS:  
> Incest, dub-con, possible underage (age not specified)


End file.
